INTRODUCTORY REMARKS. 375 



grammes of potassium hydroxide in 40 c.c. of water, and the whole diluted to 

 100 c.c. Some mercuric iodide deposits on cooling, and may be left in the 

 bottle, the clear solution being decanted as needed. 



b. Solids. 



1. Litmus or blue and red litmus paper. 

 2 Turmeric paper. 



3. Sodium carbonate, dried, Na 2 CO 3 . 



4. Sodium biborate, borax, Na 2 B 4 O 7 .10H 2 O. 



5. Sodium-ammonium-hydrogen phosphate (microcoamic salt), 



Na(NH 4 )HPO 4 .4H 2 O. 



6. Potassium carbonate, K 2 CO 3 . 



7. Potassium nitrate, KNO 3 . 



8. Potassium chlorate, KC1O 3 . 



9. Potassium permanganate, KMnO 4 . 

 10- Potassium cyanide, KCN. 



11. Calcium hydroxide, Ca(OH) 2 . 



12. Ferrous sulphide, FeS. 



13. Ferrous sulphate, FeSO 4 .7H 2 O. 



14. Manganese dioxide, MnO 2 . 



15. Zinc, granulated, Zn. 



16. Copper, Cu. 



17. Cupric oxide, CuO. 



18. Cupric sulphate, CuSO 4 5H,O. 



19. Tartaric acid, H 2 C 4 H 4 O 6 . 



20. Tannic acid, H C U H 9 O 9 



21. Pyrogallic acid, C 6 H 3 (OH) 3 . 



22. Diphenylamine, (C 6 H 5 ) 2 NH. 



23. Starch, C 6 H 10 O 5 . 



While the apparatus and reagents here enumerated are the more 

 important ones, the analyst will occasionally require others not men- 

 tioned in the above list. 



General mode of proceeding- in qualitative analysis. Every 

 step taken in analysis should be properly written down in a note- 

 book, and these remarks should be made directly after a reaction has 

 been performed, and not after the nature of the substance has been 

 revealed by perhaps numerous reactions. 



Not only the reactions by which positive results have been obtained 

 should be noted, but also those tests and reagents mentioned which 

 have been applied with negative results that is, which have been 

 applied without revealing the presence of any substance, or any group 

 of substances. Such negative results are, however, positive in so far 

 as they prove the absence of a certain substance, or certain substances, 

 for which reason they are of direct value, and should be noted. 



In comparing, finally, the result obtained by the analysis with the 



